As communication systems increase in speed and complexity in response to customer demand for increasing volume of data, a number of problems arise, one of which is an increase in electrical power consumption due to the increase in the number of circuits required and their greater switching speed. There is a need therefore to devise innovative means of reducing power consumption while simultaneously maintaining the ability to transmit and receive data at the highest possible rates.
When data is transferred in packetized form, there are many times when the aggregate data actually being transmitted is less than the total capacity of the communication channel. This creates inefficiency since there exists this unused capacity, but furthermore there continues to be electrical power consumed during these idle times.
In some prior art communication systems, power savings have been achieved by adapting the transmit power level according to the channel conditions in order to obtain an acceptable signal to noise ratio. This is commonly done in portable wireless devices where limited battery energy is available. In many such embodiments, the transmitter is shut down during substantially idle periods, and brought up to maximum power only when a fully functional full duplex communication channel is required. In other embodiments, the transmit power level is decreased when the received signal to noise ratio is above a certain threshold and the transmit power level is increased when the received signal to noise ratio is below a certain threshold.
In other prior art communications systems, such as Energy Efficient Ethernet, the physical link is shut down in order to save energy during idle intervals. However, this energy-saving technology is confined to communication channels that employ a single link.